Vernier



`F.J.'PoLAs1K VERNIER Filed Aug. 24, 1959 Aug. 27, 1940.

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Patented Aug. 27, i

ananas v rays r. renna,

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in Ill., assigner or one= Cia This invention relates to an improvement in the construction of vernier calipers, the primary object of the invention being to provide'an attachment'whereby the root diameters Vof threads may be measured and read directly on the calibration of a 'vernien My, invention may be furnished also in the form of an attachment for micrometers.

' It has been the custom, and standard practice of measuring the outside of threads, using a standard micrometer or vernier'caliper, and from the readings taken the root diameters of threads interpolated, or calculated. litv is my desire to provide a device or an improvement to such micrometer or vernier calipers, which will provide i a direct reading and thus eliminate all calculation necessary, the direct reading showing the exact dimension oi the root diameter of a thread,

Another object of the invention is the provi' v sion of such a device which has one xed jaw, and two relatively adjustable jaws, in order to sepa-f rate and adjust the same to the pitch of the helix of a screw thread permitting measurement of such threads as standard V threads, Acme threads, Whitworth threads, and any thread falling within the above category and within the range and size of the respective instruments that are used for the purpose.

Another object of the invention is the provision of a practical, durable, accurate, ecient, and useful instrument for the purpose to be described, and an` instrument of such construction which is economical to manufacture in quantity production.

Other features, objects, and advantages of my invention will become apparent by reference to the accompanying drawing and the ensuing description wherein like symbols will be used to designate like parts and in which;

Fig. 1 shows a front plane view of my improved Vernier calipers.

Fig. 2 shows a left end view thereof.

Fig. 3 shows` a right end view thereof.

Fig. 4 shows a top view looking down on Figure 1. y

Fig. 5 shows a bottom view looking inan upward direction at Figure 1.

Fig. 6 is an isometric view showing one of the important elements comprising my invention.

Fig. 7 is a fragmentary view of a threaded portion showing the jaws comprising the important features of my invention set to measure the root diameter of the thread.

Referring once again to Figure 1, it will be noted that the instrument is generally designated by the numeral t, comprising a long barf -division measuring twenty-ve thousandths of an inch.

To this bar member it, are attached two jaw members designated, respectively, i6 and Il,

which are held in place 'and located by the lowerl edge of the bar i4 and the dowel pins .designated by the numeral i5; the jaw il being held in place by the screw il whereas the jaw id is held rmly in place by the screw i6.

The jaws'are recessed as indicated at i3, and adapted to be held, normally, together at the common portion designated by the numeral`i2. Portions i9 and i8 are undercut on the respective jaw members, to provide a thinner portion which will furnish exibility for purposes later to be described.

The jaws contact one another firmly on the surface designated by the numeral 35, and one of the jaw members designated by the numeral id is provided with a boss portion to receive the meral dik-which has a spherical bottom portion an equalizing action when the said screw is threaded inwardly into the boss portion in order to separate the portions 20 of the jaws lil and il respectively.

The jaws '20 are normally in the position indicated in the view in Figure 2. Within these jaws are mounted two wedge shaped toothed members designated respectively'by the numeral 22, and having a common fiat contacting surface designated by the numeral i0. It is to lbe noted that the included angle between the two jaws in assembly and the single jaw 24 onthe opposite side is approximately 28 degrees, in order to provide ample clearance forstandard thread structure whichl is degrees,

so that there will be no difficulty in getting the jaws to seat themselves firmly in the `V shaped recesses of a thread, or the rounded recesses of a Whitworth thread as indicated in Figure 7.

vdesignated by the numeral d@ so that it will have In Figure '7 the wedge members 22 have been 4i, showing also in dotted lines the Whitworth l type of thread indicated bythe .numeral 42.

The measurement is obtained by directly reading the Vernier calipers, the use ofsuch instrug ments being `quitev familiarvto mechanics accustomed to using such instruments for measuring purposes.

' To further explain the operation of my Vernier calipers, it will be noted, that the wedge member 24 and the wedge members 22 are secured, respectively, within their holders by virtue of their extensions 25 and 2| respectively, and the screws 26 and 23, respectively. These jaws have knife edges as indicated.

Altho these jaws are made of tool steel. hardened, and ground, to resist wear, yet over a long period of time a slight amount of wear may occur, in which event the adjusting screws 23 l and 26 may be utilized in order to compensate for the wear, thus maintaining the accuracy of the instrument at all times,

'Ihe Vernier caliper is further provided with a standard designated by the numeral 33 which is mounted on the bar member I4 by virtue of a slotted portion designated 34, and is adapted to operate slidably thereover, being held in definite fixed relationship by the knurled screw member designated by the numeral 35 which is used to v either permit the member 33 to slide or to remain fixed in one place.

The movable jaw member designated by the numeral 3| is attached to the bar member |4 in slidable manner, and likewise, the adjustingl screw 32 is used to bind i-t in place and secure it in place when a reading is taken. When this screw 32 is released, the-jaw 3! is disposed to vThe Vernier 45 is attached tothe portion 28` by virtue ofV the screws 41 and the dowels 48 for the reason that it is necessary to have this instrument in accurate relationship and align- :nc-nt, and if for some reason or other the Vernier 46 should have to be removed, setting back in place in accurate location is governed by the dowel pins 43.

The slidable member 3| is 'further provided l with a Vheel portion designated by the numeral 29, and a U shaped recessed portion designated by the numeral 30 in order to give it perfect bearing and strict alignment.

The xedly secured jaw 33 is provided with a slotted portion designated by the numeral 36, in order to accommodate the knurled head knob designated by the numeral 31 which rotates upon the screw member 38 for which clearance Since one end holes are provided in the jaw 33. of the threaded portion of the screw 33 is rigidly or swivellably secured to the portion 21 by virtue of a dowel pin 3 9, and when the jaw`member 33 is held fixedly in place by the binding screw 35, then the rotation of the knurled knob 3l byvirtue of the thread 38 will cause the jaw 3| to move to the right or left with respectto 1 the jaw 33. v 70 To measure the-screw designated lby the numeral 50 the edges of the wedge shaped members 24 and 22 must contact the root of the thread as indicated in Figure 1 and Figure '7.

The principle 'of operation o`fthe Y v'ernier which is familiar to the art, `is as follows: The

Vernier caliper consists of aslider with a projecting jaw that can be moved along a graduated bar or scale also provided with a jaw, the instruvment being designed to measure accuratelyv the distance between these jaws by means of the scale and by the Vernier carried on the slider.

The Vernier has n equal parts, spaces,4 or

divisions, with aggregate length equal 'to that of n+1 of the smallest division on the scale. 'I'here- 'fore, the length of each Vernier division is n. :l: l 1 :t ll r 7L 1I.

of the' smallest scale division that is the Vernier division is jaws ofthe calipers are brought into light con' tact with the object, and the scale reading up to the zero point or index of the Vernier is ob.

served. When the index does not exactly meet the mark on the scale, the length ofthe decimal scale division is determined by observing which' Vernier mark coincides with the mark on the scale. If this coincidence occurs at the qth vernier mark. the length of the fractional scale division is evidently qL, and this amount is to be added to the direct scale reading.

In other words in this drawing it is depicted that the divisions are one fortieth of an inch or twenty-five thousandths. In this instance the Vernier is divided into 25 divisions which span `24 divisions onthe scale, hence each Vernier is equivalent to one twenty-fifth of one fortieth or .001".

Inthe illustration, the reading at the index point or cipher indicated on the Vernier is one hundred thousandth of an inch plus, whereas the mark on the Vernier which coincides exactly with a mark on the scale is 20; hence the reading is .120" of course it will be conceded that a drawing of this kind can not be as accurate as the calibration of an instrument, but has been drawn approximately correct and shows the root diameter of the screw 50 toone hundred twenty thousandths.. j

In use, my device is actually applied'as follows: a specimen which'is to be measured such asa screw 50, is placed between the jaws 22 which must first be set in agreement with the dimension representing the pitch of the thread, the thread beingplaced so that each of the jaws 22 contact the roots of adjoining recesses of any one thread on 'the one side.

This is accomplished by releasing the clamping screws 35 and 32 in order that the combined jaws 33 and 3| may be free to slide on the bar member Id until contact is felt between the knife edges of the wedges 24 and 22 respectively. When they are broughtinto light contact with the screw 50, the binding member 35- may be tightened in order to fixedly set the jaw 33. The knob 37- is then rotated in order to obtain the final contact necessary which experienced me'- 'chani-cs, as a general rule, feel and perceive aauasse in order to clamp the jaw 3| iixedly in position.

The screw 50 may be removed, and the Vernier in locked positionmay be taken to a convenient place for reading inspection or examination, especially if the specimen to be measured is in an obscure place in a machine or other mechanical device.

I believe Ihave described rather succinctly the nature and operation of my invention so that those familiar with the art will have no'trouble in using or making the same. I realize that my invention is susceptible of many'modifications, alterations, and improvements, and that the drawing herein submitted merely signiiies or depicts an exemplary or preferred form, hence I reserve the right to all such modications, improvements, and alterations, which may come within the scope and spirit of my invention, and the purview of the foregoing description; my invention being limited only by the appended or subjoined claims.

Having thus disclosed and revealed my invention what I claim as new and desire to secure by Letters Patent is:

,1. A measuring device comprising, a scale member, a jaw member xedly secured at one end of said scale member, a movable jaw member slidably secured to the said scale member, one or said jaw members provided with Ajaw spreading means comprising, two flexible arm members se'- cured to said jaw member at ,one of their ends and in superimposed relationship, two wedge shaped members secured to the free ends of the said exible arm members, a single Wedge shaped member secured to the other jaw member, the said iiexible arm members extending in the same direction, the wedge portions of the said two wedge shaped members` extending in the same direction and toward the wedge on the other jaw, and spreading means secured to one of the said flexible arm members and bearing against a surface of the said other exible arm member adapted to spread the said flexible arm members.

2. A measuring device comprising, a scale member, a jaw member 'lxedly secured at one end of said scale member, a movable jaw member slidably secured to the said scale member, one of said jaw members provided with spreading means comprising, two exible arm members secured to said jawvmember at one of their ends and in superimposed relationship, two wedge shaped members secured to the free ends of the said flexible arm members, a single wedge shaped member secured to the other jaw member, the

said flexible arm members extending in the same direction, the `wedge portions-of the said two wedge shaped members extending in the same direction and toward the wedge on the other jaw, y

the said single wedge shaped member having an included angle at the Wedge portion equivalent to, not more than, the sum of the included angles of the wedge portions of the two wedge shaped members secured to the said lexiblearm members, and spreading means secured to one of the said exible arm members and bearing against a surface of the said other iiexible arm member adapted to spread the said flexible arm members.

3. A measuring device comprising, a scale member, a jaw member xedly secured to one end of said scale member, a movable jaw member slidably secured to the said scale member, one of said @jaw members provided with jaw spreading means "comprising, two flexible arm members secured to said jaw' member' at one of their ends and in` superimposed relationship, two wedge shaped members secured tothe free ends of the said exible arm members, a single wedge shaped member secured to the other jaw member, the said exible arm members extending in the same direction, the wedge portions of the said two wedge shaped members extending in the same direction and toward the wedge on the other jaw, the said single wedge shaped member having an included angle at the wedge portion equivalent to, not more than, the sum of the included angles of the wedge portions of the wedge shaped members secured vto the said flexible arm members, the included angle of the wedge portion of the said single wedge member beingyless than the angle of a thread to be measured, and spreading means secured to one of the said exible arm members and bearing against a surface of the wedge portion of the said two wedge shaped members extending in the same direction and toward the wedge member on the other jaw, and spreading means secured to one of the said flexible arm members and bearing against the surface oi' the other exible arm member adapted to spreadl the two wedge shaped members.

5. A measuring device comprising, a xed jaw and a movable jaw, a wedge shaped member secured to one jaw, the other jaw 'having two flexible arm members secured thereto, the said ilexible arm members anchored at one of their ends in a superimposed relationship, two wedge shaped members secured to the free ends of the said iiexible arm members, the said ilexible arm members extending in the same direction, the Wedge portions of the said two wedge shaped members extending in the same direction and toward the wedge member ofthe other jaw, and spreading means comprising, screw means secured to one of said flexible arm members at a point intermediate its ends, the said screw means bearing against the surface of the said other i'lexible arm member and adapted to contactually effectuate the spreading of the said two flexible arm members.

6. A measuring device comprising, a fixed jaw bers extending in the same direction, the wedge.

portions of the said two wedge shaped members extendingin the same direction and toward the wedge member on the other jaw, the said wedge member on the one side having an inclined angle on the wedge'portion equivalent to, not more than, the sum of the included angles of the wedge portions of the said two wedge members on the opposing side.

'7. A- measuring device comprising, a xed jaw and a movable jaw, a wedge shaped member secured to one jew. the other-"jaw having two ilexible arm members secured thereto, the seid exible 'arm members anchored at one of their ends Y emesse member on the other jaw, the seid wedge member on the one'side having an included angle at thel wedge portion equivalent to, not more than, the sum of the included angles of the wedge portions of the said two wedge members of the opposing side, the included angle of the wedge portion of the said single wedge member being less than the angle of a. thread to be measured.V

FLOYD JfPOLASK., Y 

